1. Field of Invention
Various exemplary embodiments of the present invention relate generally to a voltage generating apparatus, and more particularly, to a constant voltage generating apparatus including a constant voltage stabilizer.
2. Description of Related Art
With the surge in usage of smartphones and tablets, among mobile information devices using semiconductor memory devices as storage media, the semiconductor memory devices have gained increasing interest and importance. The emergence of a wide range of applications as well as a high-speed processor or multi-core parallelism has required increased levels of performance and reliability of semiconductor memory devices.
A semiconductor memory device is a storage device that is realized using a semiconductor made from, for example, silicon (Si germanium (Ge), gallium arsenide (GaAs), or indium phosphide (InP). Semiconductor memory devices are generally classified as volatile memory devices or nonvolatile memory devices. A volatile memory device is unable to retain its stored data when the power is turned off. The volatile memory device includes a static random access memory (SRAM) device, a dynamic RAM (DRAM) device, a synchronous DRAM (SDRAM) device, or the like. A non-volatile memory device may retain its stored data even when powered off. The examples of non-volatile memory device may include a read only memory (ROM) device, a programmable ROM (PROM) device, an erasable programmable ROM (EPROM) device, an electrically erasable programmable ROM (EEPROM) device, a flash memory device, a phase-change RAM (PRAM) device, a magnetic RAM (MRAM) device, a resistive RAM (RRAM) device, a ferroelectric RAM (FRAM) device, or the like. A flash memory device is generally classified as a NOR type or a NAND type.
A semiconductor memory device includes various functional blocks. A constant voltage generating apparatus may be used to supply power to each of the functional blocks. The constant voltage generating apparatus may convert an external power supply voltage into a stabilized power voltage and supply the stabilized power voltage to the various functional blocks, i.e., driving circuits.